Opportunity Cost Calculator
What could your money be worth if invested instead of spent? See the true cost of any expense.
Every dollar you spend is a dollar that isn't compounding. Opportunity cost is the return you give up when you choose to spend rather than invest. A $500/month car payment doesn't just cost $6,000/year — at 7% returns, that money would grow to over $104,000 in 10 years. This calculator makes opportunity cost tangible, helping you decide whether any purchase is truly worth the future wealth you're giving up.
Spending $500/monthly costs $60,000 over 10 years. If invested at 7%, it would grow to $87,047 — an opportunity cost of $27,047.
Opportunity cost
Total spent
$60,000
If invested
$87,047
Opportunity cost
$27,047
Return multiple
1.5x
How to use this calculator
Amount — The cost of the expense you're considering. This can be a one-time purchase, monthly bill, or annual cost.
Frequency — How often you make this payment. One-time purchases have a smaller opportunity cost than recurring expenses because compounding amplifies frequency.
Investment return — The annual return you could earn by investing this money instead. S&P 500: ~7% real return. High-yield savings: ~4–5%.
Time horizon — How long the money would have been invested. Longer timeframes produce dramatically higher opportunity costs due to compounding.
Real-world examples
New car vs used car: $10K difference
Spending an extra $10K on a new car vs used: at 7% over 20 years, that $10K would grow to ~$38,700. The 'new car premium' doesn't just cost $10K — it costs nearly $39K in future wealth.
$500/month car payment
A $500/month car payment over 5 years = $30,000 spent. Invested at 7% instead: ~$35,800. Over 10 years (if you kept investing): ~$86,500. The car industry's favorite secret: car payments are wealth killers.
$2,000 vacation
A $2,000 vacation at age 30, invested at 7% instead, would grow to ~$15,000 by age 60. That vacation doesn't cost $2,000 — it costs $15,000 in retirement wealth. Whether it's worth it is your call.
Formula & Methodology
Future value (one-time)
- P = One-time amount
- r = Annual return rate (decimal)
- t = Time in years
Future value (recurring)
- PMT = Monthly payment amount
- r = Annual return rate (decimal)
- t = Time in years
Assumptions & limitations
- Investment returns are assumed constant. Real markets fluctuate significantly year to year.
- Taxes on investment gains are not included.
- Inflation is not factored in — use real returns (~7%) for inflation-adjusted projections.
Frequently asked questions
What is opportunity cost?
The potential benefit you give up when choosing one option over another. In personal finance, it's usually what your money could earn if invested instead of spent.
Should I never spend money then?
Of course not — the point is informed decisions, not deprivation. Some expenses are genuinely worth the opportunity cost (housing, education, meaningful experiences). The calculator helps you see the true cost so you can decide consciously.
What return rate should I use?
For long-term stock market investments, 7% real (after inflation) is a reasonable assumption based on S&P 500 history. For savings accounts, use 4–5%. For bonds, 4–6%.
Does this apply to debt payments too?
Yes, but in reverse. Paying off high-interest debt (22% APR) gives you a guaranteed 22% 'return' — far better than investing. For low-interest debt (<4%), investing the extra may be better.